In an effort to decease our page load time, we are looking at making a change so that all product images on any page past page 1 load with a place holder image. When the user clicks to the next page, it then loads all of the images for that page.
Right now, all of the product divs are loaded into a Javascript array and loaded in chunks to the page display div. Product-heavy pages significantly increase load time as the browser loads all of the images from the product HTML before the Javascript can rewrite the display div with page-specific product HTML. In order to get around this, we are looking at loading the product HTML with a small placeholder image and then substituting the appropriate product image URLs when each page is output to the display div.
From a user experience, this change will be seamless and they won't be able to tell the difference, plus they will benefit from a potentially a short wait on loading the images for the page in question. However, the source of the page will have all of the product images in a given category page all having the same image. How much of a negative impact will this have on SEO?